Fabricated non-symmetrical beam



Aug. 2, 1966 w. M. SIMPSON FABRICATED NON-SYMMETRICAL BEAM 2 Sheets-Sheet 1 Filed Aug. 9, 1965 Wag/44ml. S/MDSO/V INVENTOR.

,dzraemz/ W. M. SIMPSON FABRICATED NON-SYMMETRICAL BEAM Aug. 2, 1966 2 Sheets-Sheet 8 Filed Aug. 9, 1965 ummmnilm Al. S/MPSO/V MAL/AM INVENTOR.

BYE

United States Patent 3,263,387 FABRICATED NON-SYMMETRICAL BEAM William M. Simpson, 509 Floral Park Terrace, South Pasadena, Calif. Filed Aug. 9, 1965, Ser. No. 478,056 13 Claims. (Cl. 52634) This application is a continuation-in-part of my prior co-pending application, Serial No. 302,673 filed August 16, 1963 entitled Fabricated Structural Beam, now abandoned.

The present invention relates to a fabricated structural beam having a non-symmetrical configuration with one side being particularly adapted to carry the compressive load and the other side the tensile load; and to the method of making the same.

It has long been known to modify I-beams or channel beams of integral construction as formed at the mill, by cutting the web thereof on a zig-zag line to provide two serrated Web portions which are then separated, repositioned and then secured together at their extremities so as to form a beam having a greater height or overall beam depth than the original. Among the advantages of that type of beam structure are first, to obtain the benefits of increased height of the beam without the cost of weight of additional material; and second, to create openings in the web which will permit electrical conduits, air ducts, and the like to pass transversely therethrough when necessitated in modern structures.

However, in many cases, increasing the beam depth is not desired or cannot be tolerated since there results a corresponding decrease in height of the useable space. As an alternative to this trade-off between useable space and space needed for the various hidden mechanical, electrical, etc. systems and sub-systems typically required in a building, nonsymmetrical beams fabricated in accordance with the invention can be used for not only the primary but especially for the secondary structural rnernbers of a building superstructure. Thus, for certain anticipated loads, the fabricated non-symmetrical beam to be described may be formed of more than one type of material, generally of steels each having different strength characteristics. 'In addition, the various elements of such a beam may exhibit different cross-sectional configurations.

With this arrangement, the space needed to house the various hidden systems and sub-systems of the building can readily be provided Without, if desired, increasing beam depth. Furthermore, in more technical language, shear can be confined, not in the tension field where reductions in permissible stresses are absolutely required, but in the compression field where no stress reductions other than that allowed for the desired safety factor are necessary. Restated briefly, it is better to carry shear in compression than in tension where stress reductions are necessary and in effect constitute a penalty in that maximum utilization of material is not achieved. This, in essence, is what the British patent to Spanner, No. 487,467 dated June 21, 1938 teaches. With the present invention, however, a more eflicient use of material is achieved resulting in a reduction in dead weight of each individual structural member as Well as the over-all structural system.

It should be pointed out that the prior art reference to Spanner shows only how to stiffen a shell or skin or diaphragm with standard T or L shaped structural elements. For a more complete discussion on the combining of shear in the compression and tension fields, reference is made to part 5 of the Manual of Steel Construction, 6th edition, published in 1963 by the American Institute of Steel Construction, Inc. at page 28 and also at page 122 of the annexed commentary.

3,263,387 Patented August 2, 1966 ice With the present invention, additional advantages also become apparent. For one, the reduction in dead weight is reflected in smaller foundation size and lighter loadings. For another, the basic stability of the building is materially enhanced since the overturning forces due to uncontrolled seismic disturbance are proportionately reduced. In addition, greater flexibility is offered to the engineer and architect. The necessary strength can now be more accurately provided where needed. Economic waste is more readily controlled. The cost factor is reduced. .On locations heretofore restricted as to building heights due to underlying soil conditions, higher buildings having more useable square footage may now be erected. In short, the owners return per unit of construction cost is significantly increased.

In accordance with the invention there is provided a fabricated non-symmetrical beam comprising an elongated substantially planar member having one continuous longitudinal edge and its other longitudinal edge serrated in a toother configuration, an elongated substantially planar first flange disposed perpendicular to the planar web in engagement with the continuous longitudinal edge and secured thereto, an elongated substantially planar second flange disposed perpendicular to the planar web in engagement with the other serrated longitudinal edge and secured thereto, and support means for loading the beam in a predetermined relationship placing the first planar flange in compression and the second planar flange in tension. The cross-sectional configuration of this nonsymmetrical fabricated beam is such that at the region of minimum cross-sectional area where the centroid is displaced a maximum from mid-depth of the beam, the equation is substantially satisfied, where a and b are the distances from the beam centroid to the outer surfaces of the first and second planar flanges respectively and f (max.) and f (max.) after allowances for the desired safety factor, represent the predetermined maximum compressive and tensile stresses respectively at any point along the respective first and second planar flanges.

Other aspects of the invention include the fabricating of such non-symmetrical beams with various materials or different materials in the same beam, the use of flanges having the same or different cross-sectional areas, the forming of the interconnecting web from a one-piece plate or from a series of simple shapes properly welded together and the arranging of the planar flanges centrally or oflset relative to the web and/or parallel or inclined relative to each other.

The present invention is concerned, then, not with modifying integrally formed beams made at a mill, but rather with the fabrication of beams from separate pieces of stock that are used to form the flanges and the web thereof. The present invention is, therefore, directed to fabrication of a structure ab initio rather than the mere modification or conversion of an already existing product.

A structural beam is, in general, utilized in a horizontal configuration and loaded from above at a plurality of points distributed throughout its length. But in certain applications the beam may be vertically disposed and subjected to lateral loadings. For the purpose of the present invention it is sufficient to broadly define a beam as a structure in which one side is loaded in compression and the other side is loaded in tension, as distinguished from a column in which the entire structure is loaded compressively.

One of the premises upon which the present invention is founded is that the design requirements for the u) compression and tension sides of a beam are not identical.

An additional premise of the invention is that a nonsymmetrical web structure may be advantageously accompanied by a non-symmetrical flange structure, in which the directions of the non-symmetries are in opposite sense to each other.

Still another premise of the present invention is that, in a non-symmetrical flange arrangement for a beam, there is an economic advantage in using two flange members which are of different grades of material.

The principal object and advantage of the invention, therefore, is to provide a fabricated beam which, by being of non-syrnmetrical construction and adapted to be loaded on one particular side only, is of superior characteristics and lower cost than other competing products.

It is also an import-ant object of the invention to provide a method of making beam structures of the foregoing type.

The nature, objects and advantages of the invention will be more fully apparent from the following description considered in conjunction with the accompanying drawing, wherein:

FIGURE 1 is a perspective view of one form of beam structure provided in accordance with the invention;

FIGURE 2 is a vertical cross-sectional view taken on the line 2--2 of FIGURE 1; FIGURE 3 is a side elevational view showing the end support of the beam of FIGURE 1;

FIGURE 4 is a side elevational view showing the end support of a modified form of beam in accordance with the invention;

FIGURE 5 is a side elevational view of a central portion of another form of beam structure provided in accordance with the invention;

FIGURE 6 is a plan view showing one of the triangular shaped sections used in the embodiment of FIG- URE 5 before the tips are cropped;

FIGURE 7 is a layout drawing showing the cutting arrangement for the web structure of FIGURE 5; and

FIGURE 8 is a layout drawing showing the cutting arrangement for the web structure of FIGURES 1, 3 and 4.

Referring now to the drawing and particularly FIG- URES 1 to 3 thereof, a fabricated non-symmetrical beam 10 is seen to generally include a first or upper planar flange A and a second or lower planar flange B with a vertically disposed elongated and substantially planar web C interposed therebetween. Fragmentary support means or flange portions D are also attached to the web C at the two ends of the beam 10.

Web C has a continuous upper longitudinal edge 18 which is secured to the undersurface of the upper flange A throughout the entire length thereof. The lower longitudinal edge of web C is, however, serrated Wlth alternating truncated triangular tooth portions 111 and spaces or openings 14. Each of the tooth portions 11 has a blunt end representing a longitudinal edge portion 12 of the web C. Each of the openings 14 at its upper extremity is bounded by a longitudinal edge portion 15 of the web C. Each of the openings 14 is also bounded by straight, oppositely sloping side edge portions 16, 17, which join the edge portion 15 with the respectively associated edge portions 12.

In a more general sense it will be seen that the tooth portions 11 and intervening openings 14 may be of identical size and configuration but disposed in opposite sense relative to each other. The longitudinal side edge portions 12 of the teeth 11 are in abutting relationship with the upper surface of the lower flange B and are secured thereto.

In the embodiment shown in FIGURES 1 to 3 the beam is formed at each end by terminating the web C at such a point as to include all of the last tooth portion 11 as well as the longitudinal edge portion 15 of the next adjacent space. Fragmentary flange D is then secured to web C along the last edge portion 15, in

parallel relationship to the outer end of upper flange A. Lower rfiange B, however, is of shorter length than upper flange A and extends into engagement with and is secured to the longitudinal side edge portion 12 of the last tooth 11, but does not extend therebeyond.

Thus as shown in FIGURE 3 this end configuration of the beam facilitates supporting each end of the beam in mutually perpendicular relationship upon another beam, such as an I-beam 20. More specifically, the undersurface of the fragmentary flange D forming a part of the end of fabricated beam 10 is disposed upon the top of, and rests downwardly upon, the beam 20. In this manner the beam 10 is supported from underneath at its two ends and is adapted to receive a downwardly directed load at various points throughout its length.

In the alternate end arrangement shown in FIGURE 4 the lower flange B is of the same length as upper flange A, and the web C is terminated at its maximum width rather than at its minimum width. More specifically, web C includes one sloping side edge 16 of the last tooth 11, and the longitudinal edge portion 12 associated with that toot-h, but is then cut at a right angle along a line 17b whereby the last tooth 11 is incomplete. A hanging method of support is then utilized wherein a beam 21 having a vertically extending web is secured to the web C of beam 10 by means of a vertically disposed angle iron 22 having one leg thereof secured to the web C while its other leg is secured to the web of the beam 21.

The alternate end details as specifically illustrated in FIGURES 3 and 4 are merely illustrative and are by no means to be considered as exclusive methods of supporting the ends of the structural beam of the present invention. For example, in a cantilever beam, that portion of which can be described as having a positive bending movement, in contrast to a negative bending movement, may be fabricated in accordance with the nonsymmetrical beam 10 of the present invention. Those skilled in the art will readily understand that other modified forms of end support may be used without departing from the scope of the present invention.

In FIGURE 5, another form of non-symmetrical beam 10a is fabricated from separate triangular shaped elements E, each forming like portions 23 of the web C used in conjunction with the beam 10 of FIGURES 1 through 4. In this embodiment, the triangularly shaped elements E, reference FIGURE 6, have their tips cropped in a manner to be described and are arranged in a row with their bases 24 forming the continuous longitudinal edge 18. Specifically, the apex 25 of each element E is cut off along a dotted line 26 to form the serrated edge portion 12. The other two tips 27 and 28 are also cut off along the dotted lines 29 and 30 to form the short side edges 31 and 32 respectively. The dotted lines 29 and 30 are perpendicular to both the base 24 and the cropped apex 25 which, to repeat, forms the serrated longitudinal edge portion 12.

With this arrangement, each successive portion 23 of the beam 10a is welded to each other at the corresponding side edges 31 and 32 to form the web C which in turn is welded to the flanges A and B in the manner described in conjunction with FIGURES 1 through 4.

FIGURE 7 illustrates a cutting layout for forming the elements E used in the beam 10a. By cutting a plate P of appropriate width along the lines 33 and 34 each at an angle a separated from the other by an amount x equal to the length of the serrated edge portion 12, only the corresponding tips 27 and 28 need be subsequently cut to form the respective short side edges 31 and 32.

In FIGURE 8, another cutting layout is shown, one for forming the web C of the beam 10 as seen in FIG- URES 1 through 4. In this layout, an elongated plate P' of uniform width is cut along an undulating line 35, resulting in identical webs C and C. The tooth portions 11 of the web C are of identical configuration to tooth portions III of the web C; and it will be readily understood that upon separating the two webs from each other the tooth and space configuration that is provided is that shown in FIGURES 1, 3 and 4.

In accordance with the invention it will be seen that a substantial saving in material cost is achieved by cutting a single plate P in the manner indicated in FIGURES 7 and 8, the latter providing two complete webs, C and C. Only a single one of these webs is used in the beam 10, whereas in the beam 10a, some finite number of the elements E is used in conjunction with upper flange A and lower flange B.

At this point, it should be noted that in symmetrical beams, such as the conventional I-beam or the wide flange (WF) beams commercially available, the centroid is located at mid-beam depth. This means that the distances a and b from the centroid to the outer surfaces of the compressive and tensile flanges, the flanges A and B described herein, are equal and hence their ratio is unity. Such a condition likewise occurs in the beams 10 and 10a of the invention but only in the region where a full cross section exists, namely in the region of the serrated longitudinal edge portions 12. But, such periodic regions of full cross-section are necessary in order to secure the flange B by welding to the web C and hence complete the fabrication.

However, in the regions when the openings 14 extend the furthest across the web C and where the cross-sectional area of the beams 10 and 10a are the smallest, in these regions the centroid is shifted the greatest distance from the beam mid-depth. At these points, then, the distance a is smaller than the distance 11 (and hence the ratio of a to b) is the smallest. From this, it follows that as the openings 14 are increased in size, lesser materials are used, the centroid is shifted correspondingly more from beam mid-depth at the particular point in question along the now Ito-symmetrical beam, and the ratio a to [1 decreases accordingly.

The particular ratio desired is determined by the ratio of the maximum compressive stresses f (max.) versus the maximum tensile stresses f (max.). According to sound practice, these are determined by taking sixty percent (60%) of the yield point and termed the basic stresses F z-F For example, the yield point of ASTM type A36 commercial mild structural steel is 36,000 p.s.i. resulting in a basic compressive stress F and a basic tensile stress F, of approximately 22,000 p.s.i. Only the latter remains the same, the former varying depending upon the application. For example, the maximum permissible compressive stress f (max.) varies as the com- 7 pression flanges are laterally stayed at different intervals such as 4, 6 or 8 foot centers. Thus, it should be clear that the ratio f (max.) to f (rnax.) is seldom unity which means, in a symmetrical beam, excessive materials are employed. By reducing the quantity of materials used, the centroid can be shifted and the compressive and tension flanges loaded accordingly and in accordance with the equation In both the beams 10 and the beam 100, is will be noted that the web C is continuous along its upper longitudinal edge and discontinuous along its lower longitudinal edge; it is therefore quite apparent that the upper longitudinal edge of the web provides greater strength for the beam than does the lower edge of the web.

The lower flange B may therefore be made of stronger materials or have a larger cross-sectional area, or both, than the upper flange A. Thus, the combination of a high strength lower flange B with the low strength lower longitudinal edge of the web C may be used and made to equal or to be greater than or less than the composite strength of the low strength upper flange A and high strength upper longitudinal edge of the web C.

In order to achieve, for example, greater strength in the lower flange B it may, if desired, be made of greater width or thickness than the upper flange a, and in addition a higher strength material may be used for the lower flange B. More specifically, the upper flange A is preferably made of mild steel having a yield point of 36,000 pounds per square inch while the lower flange B is made of material having a yield point of 50,000 pounds per square inch. In accordance with presently established cost patterns for these materials it can be shown by suitable calculations that the greatest strength of the beam at the lowest cost is achieved in all instances, by making the lower flange of the more expensive but higher strength material.

Consider for the moment the following cases of a standard l2Bl4 structural beam having (1) a span of 24 feet and laterally stayed at 8 feet on center, (2) a span of 22 feet and laterally stayed at 4.4 feet centers, and (3) a span of 24 feet and an unsupported length of the compression flange of zero feet.

In all three cases, the material used for the l2B14 beam was type A36 commercial mild structural steel having a yield point F of 36,000 p.s.i. and a maximum allowable tensile stress F of 22,000 p.s.i. The maximum allowable compression stress F however, varies according to accepted practice and, for the 12B14 beam used, was found to be in (l) 9330 p.s.i., in (2) 16,950 p.s.i. and in (3) 22,000 p.s.i. Thus, the ratio r of F (max.) to F (max.) is in (1) 0.425, in (2) 0.772 and in (3) unity. Under these three conditions, the loading per foot of beam span is limited in (l) to lbs., in (2) to 346 lbs. an in (3) to 411 lbs.

In like manner, type A36 material was used in the beams 10 and 10a, each having the same span; in addition, the thickness of the web and the flanges and the width of the upper or compression flange of the beams 10 and 10a were held constant and substantially the same as the 12Bl4 beam. With beams 10 and 10a, the loading per foot of beam span in (l) was 139 lbs., in (2) was 307 lbs. and in (3) was 377 lbs. The weight per foot for the 12B14 beam is 14 lbs. in all cases; in contrast, the weight per foot of the beams 10 and 10a in (l) is 9.5 lbs., in (2) is 10.87 lbs. and in (3) is 11.96 lbs. It will be noted that in all cases the beams 10 and 10a are lighter than the 12B14 beam, being in 1) approximately 32 percent lighter, in (2) approximately 22 percent lighter, and in (3) approximately 15 percent lighter. This represents a substantial reduction in the overall dead weight of a structure and means that lighter foundation loadings are achieved. In other words a building of greater height can be erected at the same location without exceeding the dead load of a smaller structure using standard structural shapes.

Another way to look at these data is to consider the lbs. of load carried per pound of beam. With the 12Bl4 beam, this is in (1) 11.4 lbs. per pound per foot of beam span, in (2) 24.7 lbs. per pound per foot of beam span, and in (3) 26.9 lbs. per pound per foot of beam span. In contrast, the beams 10 and 10a can carry in (1) 14.6 lbs. per pound per foot of beam span, in (2) 28.3 lbs. per pound per foot of beam span and in (3) 28.9 lbs. per pound per foot of beam span. It will be noted that the beams 10 and 10a in each case carry a larger load per pound of each foot of beam span. In percentage, this represents an increase in favor of the beam 10 and 10a over the 12Bl4 beam in 1) of approximately 28 percent, in (2) of approximately 15 percent and in (3) of approximately 8 percent. Stated differently, the beams 10 and 10a in (l) are approximately 68 percent the weight of the 121314 beams and yet carry approximately 28 percent greater load per pound per foot of beam span. In (2) the beams 10 and 10a are only approximately 78 percent as heavy and carry a load approximately 15 percent greater than that allowed per foot of the 12B14 beam. Similarly, in (3) an 8 percent larger load can be carried per foot of beam span by the beams and 10a relative to the beam 12B14 and yet are approximately 85 percent its weight.

From the above, it is apparent that the non-symmetrical beams 10 and 10a fabricated in accordance with the invention are better in all respects than the comparable 12 inch 14 lb. per foot beam, the 12B14. In the examples above, the beam depth of the 10 and 10a beams was set at 11.91 inches, and the upper flange at a width of 3.97 inches. The lower flange in turn was in (1) smaller being 2.16 inches, in (2) the same being 3.97 inches wide, and in (3) larger being 5.42 inches.

All data used in the comparison made above were taken from the above mentioned Manual of Steel Construction.

The manufacturing process used in accordance with the present invention is as follows. The plates P and P shown in FIGURES 7 and 8 may be cut by burning either manually or automatically as with a pantograph' controlled torch or by shearing in an appropriate apparatus. The securing of the longitudinal edge 18 of web C to the undersurface of the flange A is preferably done by welding. The same applies in securing the tooth ends 12 to the upper surface of flange B and in joining adjacent portions 23 at the short side edges 31 and 32 to form the web C of the beam 10a.

While the beams 10 and 10a of the present invention are shown in substantially an I-beam configuration it will nevertheless be understood that the invention also contemplates a channel or modified channel type of construction if that should be desired. In addition, other materials including wood and non-ferrous metals may be used to form the beams 10 and 10a. When wood is used the elements may be assembled by gluing.

In use, the beams 10 and 10a may be turned over so that bottom flange B is upward and top flange A downward but only when the loading imposed is characterized as producing a negative bending movement as in the case of a cantilever beam in the region near its underlying support. Under such conditions, the flange B would still be carrying a tensile load and the flange A, although on the bottom, would still be carrying a compressive load. This mode of usage of the beam would be unacceptable were the bending movement positive. Thus, a definite premise of the invention is that the beams 10 and 10a are intended to be loaded such that the flange A and its associated longitudinal edge 18 of the web C is loaded in compression while the flange B is loaded in tension.

In the use of the present invention the spaces 14 permit extending conduit, air ducts, and the like in a transverse direction through the beams 10 and 10a whether existing in single or multiple configuration. It is significant to note that the configuration and vertical height of the spaces 14 permit the insertion of conduits or ducts having a maximum diameter relative to the depth of the beams 10 and 10a.

The invention has been described in considerable detail in order to comply with the patent laws by providing a full public disclosure of at least one of its forms which can be fabricated in either of the two ways disclosed. However, such detailed description is not intended in any way to limit the broad features or principles of the invention, or the scope of patent monopoly to be granted.

1 claim:

1. A fabricated non-symmetrical beam comprising, in combination,

an elongated substantially planar web having one continuous longitudinal edge and its other longitudinal edge serrated in a toothed configuration;

an elongated substantially planar first flange disposed perpendicular to said web in engagement with said continuous longitudinal edge and secured thereto;

an elongated substantially planar second flange disposed perpendicular to said web in engagement with said other serrated longitudinal edge and secured thereto;

and support means for loading the beam in a predetermined relationship placing said first planar flange in compression and said second planar flange in tenstem;

the cross-sectional configuration of the beam being such that in the region of minimum cross-sectional area the equation is substantially satisfied, where a and b are the distances from the beam centroid to the outer surfaces of said first and second flange respectively and f (max.) and f, (max.) represent the predetermined maximum compressive and tensile stresses respectively at any point along the respective first and second planar flanges.

2. The non-symmetrical claim 1 further characterized in that said beam is formed of steel and in that said second planar flange has a larger cross-sectional area than said first planar flange.

3. The non-symmetrical beam in accordance with claim 1 further characterized in that said beam is formed of steel and in that the steel used to form said second planar flange has a characteristically higher yield point than the steel used to form said first planar flange.

4. The non-symmetrical beam in accordance with claim 1 further characterized in that said support means includes at least two bearing surfaces for mounting said beam to a structure, each of said bearing surfaces defining a plane passing orthogonally through said planar web and parallel to the supporting surface on said structure.

5. The non-symmetrical beam in accordance with claim 1 further characterized in that said support means includes a bearing surface at each end of said beam for mounting said beam to a structure, each of said bearing surfaces defining a plane passing orthogonally through said planar Web and parallel to said first planar flange and to supporting surfaces on said structure.

6. The non-symmetrical beam in accordance with claim 1 further characterized in that said support means includes at least two bearing surfaces cooperatively associate-d with said planar web for mounting said beam to a structure, each of said bearing surfaces defining a plane passing orthogonally through said planar web and parallel to said first and second planar flanges and to supporting surfaces on said structure.

7. The non-symmetrical beam in accordance with claim 1 further characterized in that said support means includes at least two bearing surfaces cooperatively associated with said planar web for mounting said beam to a structure, each of said bearing surfaces defining a plane passing orthogonally through said planar web along a line parallel to said first planar flange and at a point intermediate said centroid and said first planar flange.

8. The non-symmetrical beam in accordance with claim 1 further characterized in that said planar web includes a plurality of substantially triangularly shaped spaced apart openings, the base of each of said openings coextending between two adjacent ones of said serrated longitudinal edges and the apex of each of said openings extending transversely a predetermined distance towards said continuous longitudinal edge to form the regions of said minimum cross-sectional area.

9. The non-symmetrical beam in accordance with claim 1 further characterized in that said plan ar web includes a plurality of openings periodically disposed between adjacent ones of said serrated longitudinal edges to position the centroid of said beam nearer said first planar flange within limits satisfying said equation in the region of said minimum cross-sectional area.

[beam in accordance withv 10. The non-symmetrical beam in accordance with claim 1 further characterized in that said planar web comprises a plurality of substantially triangular shaped portions welded together with their bases forming said continuous longitudinal edge, the apex of each of said portions being cropped to form said longitudinal serrated edge.

11. The non-symmetrical beam in accordance with claim 1 further characterized in that said planar web comprises a plurality of triangularly shaped portions, the tips of each portion being cropped to provide two parallel short sides each perpendicular to the base of said portion and to the cropped apex of said portion, adjacent ones of said portions being Welded at correspondingly short sides to form said continuous longitudinal edge and said cropped apex forming said serrated longitudinal edge.

12. The non-symmetrical beam in accordance with claim 1 further characterized in that each of said elements is formed of non-ferrous metals.

13. The non-symmetrical beam in accordance with claim 1 further characterized in that each of said elements is formed of wood and assembled by gluing.

References Cited by the Examiner UNITED STATES PATENTS 1,563,117 11/1925 Tonnelier 52--634 1,644,940 10/ 1927 Moyer 52634 2,941,635 6/ 1960 Harris. 3,140,764 7/1964 Cheskin 52634 3,141,531 7/1964 Montgomery 52-634 FOREIGN PATENTS 826,634 1952 Germany. 487,467 1938 Great Britain.

FRANK L. ABBOTT, Primary Examiner.

20 R. A. STENZEL, Assistant Examiner. 

1. A FABRICATED NON-SYMMETRICAL BEAM COMPRISING, IN COMBINATION, AN ELONGATED SUBSTANTIALLY PLANAR WEB HAVING ONE CONTINUOUS LONGITUDINAL EDGE AND ITS OTHER LONGITUDINAL EDGE SERRATED IN A TOOTHED CONFIGURATION; AN ELONGATED SUBSTANTIALLY PLANAR FIRST FLANGE DISPOSED PERPENDICULAR TO SAID WEB IN ENGAGEMENT WITH SAID CONTINUOUS LONGITUDINAL EDGE AND SECURED THERETO; AN ELONGATED SUBSTANTIALLY PLANAR SECOND FLANGE DISPOSED PERPENDICULAR TO SAID WEB IN ENGAGEMENT WITH SAID OTHER SERRATED LONGITUDINAL EDGE AND SECURED THERETO; AND SUPPORT MEANS FOR LOADING THE BEAM IN A PREDETERMINED RELATIONSHIP PLACING SAID FIRST PLANAR FLANGE IN COMPRESSION AND SAID SECOND PLANAR FLANGE IN TENSION; THE CROSS-SECTIONAL CONFIGURATION OF THE BEAM BEING SUCH THAT IN THE REGION OF MINIMUM CROSS-SECTIONAL AREA THE EQUATION 